[Mlir-commits] [mlir] [mlir][OpenMP] Translate task_reduction on omp.taskgroup (PR #199565)

[Sairudra More]

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@@ -3643,6 +3646,183 @@ convertOmpTaskloopContextOp(omp::TaskloopContextOp contextOp,
   return success();
 }
 
+/// Build an outlined init helper for a task_reduction declare_reduction op.
+/// Signature: void(ptr %priv, ptr %orig). For non-byref reductions, the init
+/// region's mold argument is mapped to the value loaded from %orig, and the
+/// yielded scalar is stored into %priv.
+static llvm::Function *
+emitTaskReductionInitFn(omp::DeclareReductionOp decl, StringRef baseName,
+                        LLVM::ModuleTranslation &moduleTranslation) {
+  llvm::Module *llvmModule = moduleTranslation.getLLVMModule();
+  llvm::LLVMContext &ctx = llvmModule->getContext();
+  llvm::Type *voidTy = llvm::Type::getVoidTy(ctx);
+  llvm::Type *ptrTy = llvm::PointerType::getUnqual(ctx);
+  llvm::FunctionType *fty =
+      llvm::FunctionType::get(voidTy, {ptrTy, ptrTy}, false);
+  llvm::Function *fn =
+      llvm::Function::Create(fty, llvm::GlobalValue::InternalLinkage,
+                             baseName + ".red.init", llvmModule);
+  fn->setDoesNotRecurse();
+  fn->getArg(0)->setName("priv");
+  fn->getArg(1)->setName("orig");
+
+  llvm::BasicBlock *entry = llvm::BasicBlock::Create(ctx, "entry", fn);
+  llvm::IRBuilder<> b(entry);
+
+  llvm::Type *elemTy = moduleTranslation.convertType(decl.getType());
+  llvm::Value *origVal = b.CreateLoad(elemTy, fn->getArg(1), "omp.orig");
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Saieiei wrote:

@MattPD, I updated the init helper to mirror the regular reduction path: it now loads from `%orig` only when the mold argument is non-pointer. For pointer-typed reductions, it forwards `%orig` directly, so the init helper lowers to `store ptr %orig, ptr %priv` without the spurious load.

I left the combiner unchanged after checking the regular reduction lowering, since the by-value combiner path also loads the pointer operands there. Added pointer-typed taskgroup reduction test coverage for this case.

https://github.com/llvm/llvm-project/pull/199565